Continuous Variable Transmission for Hybrids?

Can anyone tell me where I can find an answer to the question - "Why do Hybrid electric vehicles need a Continuously Variable Transmission gearbox when BEVs do not"

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  • I’m not sure that I can give a definitive answer, but I can add to the information.  An electric motor can have high torque from zero revs throughout the revs range so an all- EV does not need a gear box.

    There are two types of hybrid, “parallel” or “serial.  In a parallel configuration the wheels can be driven by both an electric motor and a petrol motor, that also charges the battery.  As the petrol motor drives the wheels directly it needs a gearbox to keep the engine revs within the acceptable torque range similar to a non-electric car.   In  a “series” hybrid, the electric motor drives the wheels directly so does not need a gearbox.  The battery provides power to the electric motor and is charged by a petrol generator (the “hybrid” bit).  This motor is constant revs for efficiency so does not need a variable gearbox.

    David

  • Thank you both. It looks as though the serial type is rare, so most hybrids bought in UK are parallel.  Hence having to have the rather iffy CVTs.

    I am glad, so far, after a yera's driving our Kona BEV, that we made that decision.

  • The Nissan e-power range uses the series configuration.

    www.nissan.co.uk/.../e-power-cars.html

    There is a diagram that explains the series/parallel arrangement there.

    David

  • Mine is a plug-in hybrid and in all modes the power goes through the gearbox (auto, multi-speed not CVT). It has flappy paddles to change gear if you want, this works whether the engine is running or on battery only. I do know that the gearbox has several clutches in it, but that may be common to automatic transmissions anyway.

  • Yes, but a hybrid IC engine that just charges a battery at optimum revs and then cuts out until battery drops to 75% has the best of both worlds. No gear box needed and can be charged at home if cheaper.

    However, the ICE needs to be switchable off in city centres or it will have to pay congestion charges and other clean air taxes.

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  • Yes, but a hybrid IC engine that just charges a battery at optimum revs and then cuts out until battery drops to 75% has the best of both worlds. No gear box needed and can be charged at home if cheaper.

    However, the ICE needs to be switchable off in city centres or it will have to pay congestion charges and other clean air taxes.

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